The level of cyclic nucleotides will be measured in ixodid tick salivary glands after treating glands with substances that affect their ability to secrete fluid. Special attention will be given to possible interrelationships between levels of calcium and cyclic nucleotides. Enzymes regulating cAMP (adenylate cyclase and phosphodiesterase) will be studied. The question of how at possible changes in specific membrane phosphoprotein(s) during the fluid secretory process. Preliminary investigations will be made to determine the feasibility of using in vitro gland preparations to study the nature and control of enzyme and cement material secretion.